The invention concerns bicycles.
There are several well known brands of folding bicycles on the market.
These brands are roughly speaking folded by dividing their rigid and more bulky parts such as the frame, forks and handlebar into one or more units which are then superimposed by means of articulations.
This method however includes a number of drawbacks.
The bicycle so folded is always too bulky, the operations of folding it for transport and opening it out for use are complex and the ultimate effect causes wear on basic parts such as the frame, forks and handlebar.
The prior reference EP 0 565 760 discloses a collapsible bicycle in which the rear wheel is supported by a three-fork triangular structure, rotatable on the axis of the pedal unit and fixed, when ready for use, to the top of the frame comprising two sharply arched longitudinal tubes.
When said rotatable structure is detached from the frame, the rear wheel can be placed underneath in contact with the frame.
It is thus clear that the bulk of the folded bicycle remains considerable and in practice does not solve the problems that such a bulk creates.
The prior reference U.S. Pat. No. 3,990,717 makes it possible to superimpose the two wheels, chosen for their limited size, making use of a substantially square frame, there being double joints at the four corners so that the four sections of the frame can be placed over one wheel and the second wheel over that one.
When the bicycle is ready for use the frame is kept rigid by a set of tie rods.
Clearly, reducing the bulk to substantially that of the two superimposed wheels is a complex operation and also means that the structure of the bicycle consists of a large number of parts.
In conclusion, this bicycle is very expensive and its conversion from the form for transport to that of use is necessarily a complex matter.
The above invention discloses a method for quickly folding the essential components in a bulk equivalent to that of the wheels laid side by side so that the bicycle in this compact form can be stowed in the boot of a car and opened up for use when required as will be explained below.
Subject of the invention is a bicycle that can be folded for transport so as to occupy approximately the bulk of its wheels laid side by side.
Here follows a description of the main characteristics needed to obtain this result.
At the upper end of the rear fork is an articulation, corresponding to the lower ends of the frame, with its axis parallel to that of the rear wheel, that enables the rear wheel to be brought up to the top of the frame.
The pedal unit with gear is supported above by a tubular bar at whose upper end is an articulation, on one lower end of the frame, the axis of which is parallel to that of the pedal unit, permitting the gear to be brought up to the top of the frame.
The bar of the pedal unit can be associated to the rear fork by a hand-operated locking device placed at the top of a sort of locking triangle formed of the conjunction of two short bars, at an angle one from another, that depart from the upper and lower sides of the pedal unit ensuring stability of the rear fork and of the pedal unit when the bicycle is opened out for use.
The handlebar, shaped like an upward-facing U, is fixed to a rod that can be joined to the front fork, by means of a manually-operated locking device, permitting the handlebar to rotate on an axis orthogonal to said rod, the handgrips then facing downward roughly coplanar with said rod.
The front fork is supported by an upper rod freely turning inside a tube fixed to the forward end of the frame.
The handlebar rod slides inside a steering column at whose upper end is a hand-operated locking device fixed to the fork of the front wheel, above it by means of a lateral hinge lying on a geometrical plane transversal to the upper rotation rod of said fork and lying at approximately 45xc2x0 to the longitudinal plane of symmetry of the front wheel, and sideways by means of a locking device placed at the top of said fork""s upper rod.
The tube supporting the front fork""s upper rod is fixed by a bracket to the front of the bicycle frame, by means of a joint, whose axis is substantially orthogonal to the rear wheel, and of a hand-operated locking device.
The saddle is supported by a rod that slides inside a tube, joined at the lower end of the frame by an articulation parallel to the rear wheel close to the articulation of the fork.
By means of a hand-operated articulation and locking device at the top of the tube, joined by a tie rod that slides inside a tubular extension of the frame, both saddle rod and tie rod can be locked in the desired position.
The pin of the left pedal is supported by a hand-operated locking device, at the end of the pedal crank, to permit rotation of said pin on an axis orthogonal to the pedal crank so that, when packed for transport, said crank is substantially parallel to the back wheel.
By releasing, in succession, the locking devices on the bicycle ready for riding, it can be prepared for transport by moving both gear and rear wheel to the upper part of the frame, turning down the handlebar, pressing the handlebar rod into its steering column, turning the column 45xc2x0 round the hinge at the bottom against the front wheel, rotating the group comprising front wheel, front fork, handlebar column and handlebar itself against the back wheel and pedal unit, pushing the saddle rod into its tube and the saddle""s tie rod inside the tubular extension of the frame then rotating said column towards the frame, turning the left pedal pin so that it is beside said group, by doing all this the bulk of the bicycle can be reduced to practically that of the two wheels when placed side by side.
In a preferred type of execution the frame is formed of a tube bent into a longitudinal fork, symmetrical in relation to the bicycle""s vertical geometrical plane of symmetry and inclined towards the front wheel with a curved front section and two arms, the left arm extending downward to bend at about 90xc2x0 inside the bicycle, and the right arm completed by an external lateral extension bent at about 90xc2x0 towards the rear fork until the ends of said arms reach a coplanar position with a joining bridge lying on the bicycle""s longitudinal geometrical plane, both slightly diverging.
Rear fork and pedal unit articulations are placed respectively at the ends of said left and right arms.
On the left arm of the rear wheel""s fork there is preferably a triangular extension substantially fixed to the upper and lower ends of the fork, said extension facing inside the bicycle, with a U-bolt on the downward facing end, amplitude corresponding to the lower bar of the locking triangle that comprises the pedal unit.
The locking device of the pedal unit and rear fork consists of a pin mounted orthogonally in the top of said locking triangle, that penetrates inside the rear fork, and of a lug having in it a recess made at the connecting point of an extension of the rear fork facing away from the bicycle, in which recess said threaded pin can be pressed and locked by a wing nut after insertion of the lower bar of the locking triangle inside said U-bolt.
The locking device for the handlebar consists of two half-bearings, one facing upward forming a semi-cylindrical slot equal to the diameter of the central crosspiece of the handlebar, fixed to the rod of said handlebar, and the other substantially the same, facing towards the first, both connected by screws through holes and fixed by wing nuts.
The locking device of the handlebar rod in the steering column consists of a halfring, fixed to said column, that can be tightened as required by a clamp comprising a transversal screw and a wing nut.
The locking device between the steering column and the rod of the front fork consists of a tongue fixed to the steering column at a certain distance from the lower hinge, that can be connected to a square fixed to the upper rod of said front fork by a screw and wing nut.
The locking and articulation device to fix the bracket of the front wheel fork tube onto the frame, consists of a small practically horizontal fork, facing towards the front wheel, having in it two parallel holes, one for articulation between said small fork and the bracket, and the other to take a screw, through a hole in said bracket, fixed by a wing nut to lock the device when the bicycle is in use.
The locking device for the tube into which the saddle""s rod slides, consists of a half-ring with a perforated tongue and transversal screw with wing nut to tighten said half-ring and therefore lock said rod in the two positions, fully extended for riding and pushed into the tube for transport.
On this screw is a head placed at the end of the saddle""s tie rod that slides into the tubular extension of one arm of the frame so that by locking said device, the position of the tie rod is locked, fully extended for riding or fully inside for transport, as rotation of the tube on its ""articulation at the lower end of the frame causes rotation of the perforated tongue on the locking device containing the screw with wing nut.
Locking this rotation therefore also locks the saddle""s tie rod in position and consequently the tube as well.
The locking system for the pin of the pedal on the left pedal crank in the two positions, for riding and for transport, consists of a short bar fixed to said pin, said bar freely rotating longitudinally inside the pedal crank and controlled by a transversal pin, served by a spring, that can penetrate as required in one or other of the transversal holes in said bar corresponding respectively to the position of the pedal pin orthogonal to the pedal crank or on the same plane as the pedal crank.
The effect of this feature is to compress the volume of the bicycle, when folded for transport, substantially within a parallelepiped measuring cm 40xc3x9750xc3x9720, if wheel diameter is 40 cm, or else within a parallelepiped measuring cm 50xc3x9760xc3x9720 if wheel diameter is 50 cm.
In one advantageous variant nearly all folding parts of the bicycle can be balanced.
According to this variant, inside the lateral extension of the right arm of the frame, there is a cylindrical helical compression spring resting on a base plate welded to the end of said extension, through which passes a metal wire hooked uppermost to an upper head of the spring and freely emerging below from a hole in said base plate, then hooking onto a clamp placed on one arm of the rear fork of the bicycle close to its articulation with the frame.
The spring is preloaded so as to assist in balancing the rear fork complete with rear wheel.
On leaving the head of the spring, the wire attached to it passes through the lateral hole that connects the right arm of the frame to its extension, and becomes attached to a clamp placed close to the tip of the saddle""s tie bar so that when said tie bar is pressed inside the tubular expansion of the right arm of the frame, the wire becoming extended enters in synergy with the spring, assists in balancing the rear fork and ensures its stability in the folded position with the rear wheel mainly inside the frame.
A cylindrical helical compression spring is placed at the end of the left arm of the frame and makes contact with a plate welded at the end of said arm practically at the position of the articulation of the bar that supports the pedal unit and that has at its upper end a head with a clamp to which a metal wire is attached, said wire passing through the spring and freely emerging from a central hole in the plate after which it hooks onto a clamp placed on said bar supporting the pedal unit close to its articulation on the frame thus assisting balancing of the pedal unit together with its gear and chain.
Inside the handlebar rod is a cylindrical helical compression spring that makes contact uppermost with a plate welded substantially at the top end of said rod.
A metal wire fixed to a clamp on the spring""s lower head passes through said spring and emerging freely from a central hole in the plate hooks onto the central crosspiece of the handlebar.
When the bicycle is folded up, rotation of the handlebar pulls on the wire and compresses the spring so counterbalancing tire handlebar""s weight.
At the lower end of the handlebar""s steering column is a cylindrical helical compression spring that makes contact substantially with the lower end of said column and therefore with the plate that connects the column with a hinge supported by a bracket fixed to the front fork of the bicycle and that uppermost has a head with clamp to which is attached a metal wire that, passing through the spring, freely emerges from a hole in said plate and becomes attached to a clamp substantially in the centre of said bracket.
Therefore, on folding up the bicycle for transport, the handlebar column is bent up against the front wheel, the helical spring becomes compressed when pulled by the wire so balancing the weight of the column with the handlebar.
The device placed at the end of the left pedal crank, to position the pedal orthogonal to the crank when in use, or on said crank""s geometrical plane for transport, consists in a particular configuration of the end of the pedal crank comprising, outwards in succession, a length of constant square cross section, a collar, an end length of a constant square section and a locking washer mounted frontwise on the end of the pedal crank by a screw of a diameter greater than the cross section of the pedal crank.
Sides of the square section and collar diameter are substantially equal. At the end of the pedal pin is a head connecting with the pedal crank consisting of a squared ring whose internal dimensions are substantially the same as those of the end cross section of the pedal crank, permitting said head to slide freely on the ends of said crank.
A ring nut, placed on said end of the pedal crank, has a central hole in it of a constant square section the dimensions of which are substantially the same as those of the end of the pedal unit.
Placed diagonally in one corner of the hole in said ring nut is a U-shaped elastic metal fork whose arms are securely fixed to extensions made substantially in the centre of the sides forming the corner of the above hole, whose central part cuts through said corner.
The ring at the end of the pedal pin can therefore be placed on the square end of the pedal crank when the bicycle is in use, when the pin is orthogonal to the axis of the pedal crank and the ring nut at the position of the collar.
Spontaneous movement of the ring nut towards the internal square area of the pedal crank is however prevented because the fork placed diagonally to a corner of the hole in the ring nut moves spontaneously to one side of said end of the pedal crank causing the square hole in said ring nut to become displaced in relation to the square body of said end of the pedal crank.
The pedal consequently remains locked in the working position.
When it is desired to move the pedal for transport, the elastic fork can be pressed by hand to free the corner of the square hole in the fork and allow the ring nut to slide towards the inside of the pedal crank so that it coincides with the length of a square section.
In this way the ring on the pedal pin can pass to the position of the collar, rotating until it lies on the same geometrical plane as the pedal crank and sliding to the end of the square section of the pedal crank leaving the ring nut free to resume its position near the collar.
In that position the ring nut is free to rotate and, pressed by the elastic fork, the corners of its hole once more interfere with the sides of the square end of the pedal crank, so fixing the pedal in its transport position.
The invention offers evident advantages.
By moving a few locking devices, easily done by hand, the pedal unit and rear wheel can be quickly moved to the upper end of the frame, the handlebar made substantially coplanar with its steering column, said column bent against the front wheel and the whole complex, comprising said front wheel and the handlebar, bent onto the rear wheel and pedal unit, the pedals themselves having already been turned to become parallel with the rear wheel.
Bearing in mind that the frame practically consists of a longitudinal fork, the upper end of the rear wheel can be placed inside said fork.
The saddle bar can be pressed completely into its column and this latter be folded towards the frame of the bicycle so that the saddle is practically matching with the top of the frame.
It will be seen from-the above that, when folded up for transport, the total bulk of the bicycle can be comprised within the volume of a parallelepiped whose height and width are substantially that of wheel diameter.
If wheel diameter is 40 cm, total bulk is approximately cm, 40xc3x9750xc3x9720, while if wheel diameter is 50 cm, total bulk is about cm 50xc3x9760xc3x9720.
The ease of locking and releasing the devices and the security they offer when the bicycle is ridden, mean that the vehicle can be used with maximum comfort and satisfaction in any place suitable for bicycle riding.
The variant execution, in which nearly all the heavy parts of the bicycle such as the fork and back wheel, the pedal unit and gear, the handlebar and steering column, can be balanced by springs associated to metal wires inside the steering column and handlebar rod, greatly facilitates changing from the riding position to that for transport which becomes a simple and convenient operation avoiding for users all the effort generally connected with transforming a folded bicycle into one ready for use.
Compared with known types of folding bicycle, the one here invented presents exceptional compactness and a surprisingly easy changeover from one form to the other, offering greatly increased comfort to users who really can benefit from an extremely useful xe2x80x9caccessoryxe2x80x9d for travelling over any type of ground, fully exploiting the features typical of bicycles even when the chosen area is reached by motor vehicles or other means.